[Digoxin therapy in patients with long-term digitalis therapy. Comparison of the digoxin blood level after oral administration of digoxin and beta-methyldigoxin].

Unlabelled: The serum digoxin levels of 23 patients were measured by radio immune assay. The patients were divided into 2 groups receiving either 0,5 mg digoxin b.i.d. or 0,25 mg digoxin b.i.d. orally after having been changed from a maintenance dose of 0,2 mg beta-methyl-digoxin b.i.d. The applicated digoxin was the preparation Lenoxin. The question was whether typical or reduced maintenance doses of digoxin in the new preparation reached therapeutic digoxin serum levels in the absence of renal insufficiency.

Results: 1. The maintenance dose of 0,2 mg beta-methyl-digoxin produced stable serum digoxin levels within non-toxic range in all patients; 2. the dosage of 0,5 mg digoxin (group 1) induced accumulation to toxic levels (2,14 mg/ml). A change to 0,25 mg digoxin led to therapeutical serum levels; 3. when using the dosage of 0,25 mg digoxin from the onset of the test (group 2) accumulation was avoided and normal serum digoxin levels were observed during the test period.